Incidence of Bois Noir phytoplasma in different viticulture regions of Spain and Stolbur isolates distribution in plants and vectors

The incidence of Bois Noir (BN) disease in grapevine plots, the population of the vector Hyalesthes obsoletus , and the distribution of stolbur phytoplasma isolates were studied over a 4 year period in five regions of Spain. BN incidence in affected plots ranged from 1 to 75 %. A study of the H. obsoletus population indicated that individuals of this insect vector were identified in most of the sampled plots with low populations, from 0.25–5 individuals per aspiration. The population peaks of H. obsoletus were reached at different dates between June 6th and July 24th, depending on the sampled zone and the year. The percentage of H. obsoletus individuals carrying the phytoplasma showed an average of 55 %. In Aragon, this percentage rose to 76 %. The strain tuf-b of stolbur phytoplasma was the most prevalent type in grapevine plants and H. obsoletus , except in grapevine plants from La Rioja where the strain tuf -a was detected in most plants. A study of the vmp1 gene revealed the presence of four different isolates in grapevine plants and H. obsoletus .